MOA means minute of angle.One MOA is so close to one inch at 100 yards(actually 1.047") that most people just call it one inch at 100 yards.Since it is an angle it changes with distance and equals 2" at 200 yards ,3" at 300 yards etc.Ballistic co-efficient refers to how well a bullet cuts through the air.A higher ballistic co-efficient means it will maintain it's velocity better over long distances and therefore drop less than a bullet with a lower ballistic co-efficient.Generally pointed boattails have the highest ballistic co-efficients while flat based round noses have the lowest ballistic co-efficients.